Process of transporting a slurry in a pipeline



United States Patent 3,380,784 PROCESS OF TRANSPORTING A SLURRY IN APIPELINE Parke 0. Yingst, Golden, and Thomas I. Sharps, Boulder,

(3010., assignors to Northern Gas Products Company,

Omaha, Nelm, a corporation of Delaware Filed Feb. 16, 1965, Ser. No.433,049 14 Claims. (Cl. 302-66) ABSTRACT OF THE DISCLOSURE Disclosed isa process of transporting in a pipeline a solid material, such aspotash, suspended in a liquid petroleum product, such as crude oil. Thesolid material is suspended in the oil by means of a copolymer of methylvinyl ether and maleic anhydride.

This invention relates to the simultaneous transportation by pipeline ofa liquid petroleum product containing granules of one or more solidmaterials.

Since the cost of shipping solid materials by conventional means such astruck and rail is often excessive, investigation has previously beenmade as regards the feasible transporting of granular or particulatematerials such as potash, soda ash, sulfur, sodium sulfate, phosphaterock, iron ore and coal suspended in a liquid petroleum product by meansof a pipeline. The economics of such a transportation means is obviousin those localities where such solid materials are mined adjacent toareas from which petroleum products are recovered and shipped bypipeline. This transportation means is, of course, equally applicablewhere such solid materials and liquid petroleum products are reshippedfrom the same general depot areas.

Although the transportation of solid materials in liquid petroleumproducts has been studied quite extensively, a number of problems havebeen met and one of the greatest has been the normal tendency for thesolid material to settle out of the suspending liquid medium withcompaction that resists ready redispersion.

When solids of various particle sizes are dispersed in a liquid mediumand permitted to settle in an unhindered manner the large particlessettle out first, then the finer and finally the finest size particlessettle in layers one upon the other. The resulting settled mass iscompact and can only be redispersed with difficulty if at all.

In hindered settling the solids do not separate and settle according tosize but instead settle as a mass.

One approach to reducing compaction where solids are unhindered is topump the liquid slurry through the pipeline at a high velocity. This,however, results in increased cost because of the high pumpingvelocities required.

As shown in Cross U.S. Patent 2,610,900, various solid materialsincluding potash (potassium chloride) require special means to obtainuseful suspending capacity in liquid petroleum products when transportedin a pipeline. Cross states that by regulating the viscosity and/or theparticle size of the solid material, the velocity can be reduced and thesolid materials maintained adequately in suspension to permit itstransportation in the pipeline.

Cross states that the particles should be small enough to pass a 100mesh screen. However, particles even of that size and smaller tend tostratify and compact upon settling. As a slurry is pumped through apipeline, or when pumping stops, the larger particles settle morerapidly than the smaller particles. When the various size particlessettle naturally, due to the different settling veloci- 'ice ties, theytend to stratify and compact quite densely in the bottom of the pipe.The denseness of the compaction can make is very difiicult, if notimpossible, to start the stream moving again after the pipeline is shutdown.

It is also known that particles settle more rapidly and withconsiderable compaction from slurries containing a lower percentage ofsolids. As the percentage of solids is increased, hindered settlingresults. It might be desirable, however, for economical reasons toemploy slurries which contain a lower solids content, such as of aboutto solids, rather than the more concentrated slurries in the area ofabout solids or higher even though the higher concentrated slurries givea more hindered settling effect. The subject invention allows for suchflexibility.

Cross also teaches in his patent that settling can be reduced byviscosity control by putting in various viscosity increasing materials.While the settling may be reduced, the viscosity regulating approach isnot convenient, leads to increased operating costs in pumping theviscous material through the pipeline and does not solve the problem ofstarting the pipeline in operation after a shutdown period during whichcompaction of the settled solids has occurred.

It 'has been found according to the subject invention that a slurrymixture of particles of a solid material dispersed thoroughly in anormally liquid petroleum product, and which mixture contains a smallamount of a polymer of methyl vinyl ether and maleic anhydride, gives ahindered slurry which can be forced through a pipeline to a collectingdepot with high efficiency, comparatively low power consumption andcompaction reduced to a low level which does not interfere withtransportation in the pipeline or restarting flow of the slurry afterstoppage. The inclusion in the slurry of a small amount of a polymer ofmethyl vinyl ether and maleic anhydride causes the particles ofdispersed solid material to fiocculate and brings about a far greaterhindered settling condition than could be achieved by increasedconcentration alone.

This effect is achieved even at low concentrations of solids such asbelow 30% and even down to 20%. Such a slurry stream can be pumped at alow velocity, thus requiring less power and furthermore, if the materialdoes have occasion to settle to the bottom of the pipe, there is nosignificant stratification of the various size particles, the settledmass is more bulky and much less compact than has been obtained in thepast and is much more readily redispersed. Although the solids settlefaster from such a slurry than from a slurry containing no addedpolymer, the solids from the latter settle as beach sand while with thepolymer they are somewhat gelatinous. This property makes the thickenedsolids more fluid, even at a high percentage of solids and reduces theproblem of pumping, together with reduced friction head loss.

Because of the high stability of the dispersion obtained with thepolymer it can be added at the intake end of a pipeline. The violentaction in a pipeline will not break up the agglomerated particles orflocs in transit. The hindered condition of the slurry is thusmaintained throughout transport in a pipeline.

While a large number of solid materials can be conveniently transporteddispersed in a liquid petroleum product the invention is particularlyuseful for transporting water-soluble solid materials and particularlypotash (potassium chloride).

The concentration of solid materials in the slurry can vary considerablybut usually the slurry will contain about 25 to 50% by weight of solids,such as potash.

The particulate solid materials in the slurry should generally be quitesmall and advisably the diameter of the particles should be about 2.00mm., which is the sieve opening of a mesh screen, or less. Because ofthe fiocculating capacity of the polymer used to agglomerate theparticles, it is unnecessary to carefully classify the particles of thesolid material into different sizes or grades based on average diameterrange as is usually the case with prior art transporting processes.Since the suspending ability of the polymer maintains the solidparticles in suspension for sufficient time and because upon settlingthe solids do not stratify or compact, it is unnecessary to carefullycontrol particle size. Of course, particles should not be unduly largeor unnecessarily small so as to negate the advantages that areobtainable by employment of the invention.

A commercially available copolyrner of methyl vinyl ether with maleicanhydride which can be used is Gantrez AN169. It contains a one to onemolar ratio of methyl vinyl ether to maleic anhydride with repeatingunits of the formula It has a specific viscosity of about 2.6-3.5 asdetermined on a solution of 1 g. of the copolymer in 100 ml. ofmethylethylketone at C.

Only small amounts of the polymer of methyl vinyl ether with maleicanhydride need be included in the slurry to effect suitableagglomeration, concomitant suspension and hindered dispersion. Theslurry may contain about 0.005 to about 0.50 pound of polymer per ton ofsolid materials, such as potash, in the slurry with a representativesuitable optimum amount being about 0.02 pound per ton of solidmaterials.

In order to obtain thorough distribution of the polymer through theslurry, it is advisable to first dissolve the polymer in a solvent whichis miscible with the liquid petroleum product to be employed in thetransportation system. Although many solvents might be used, because ofits availability and low cost, methanol is the solvent of choice. Itdissolves not only the polymer but is totally miscible with the liquidpetroleum product. Such solvent need only be used in an amount adequateto dissolve the polymer and thereby obtain its distribution throughoutthe liquid petroleum product. A 0.01% solution of the polymer inmethanol added to give about 0.1 pound of polymer per 1,000 pounds ofsolids (potash) is particularly useful. Other solvents for the polymerwhich can be used are propanol, ethyl acetate, acetone, benzaldehyde,phenol, pyridine and cyclohexanone. The amount of polymer added willgenerally not exceed 1% of the solution because higher amounts dissolveslowly and make the solution undesirably thick.

The invention is useful with a wide variety of crude and refinedhydrocarbon oils of various viscosities. The addition of more polymer tothe less viscous oils than to the heavier oils is to be expected.Furthermore, in order to obtain optimum results the solids concentrationshould usually be greater in the lighter oils than in the more viscousoils.

Not only does the polymer of methyl vinyl ether and maleic anhydridefacilitate transportation in a pipeline but the copolymer alsofacilitates separation of the solids from the oil whether the separationbe by filtration, cycloning or other means. Even in cases where thepolymer is not used in the slurry when transported by a pipeline it isadvantageous to incorporate the polymer in the slurry when separationfrom the oil is to be effected.

Pipeline experimental tests have shown that at any specific velocitybelow the transitional velocity, the friction head loss is less forthose slurries to which the polymer has been added. Higher velocities,but with lower friction head loss, are required to reach the criticaland transitional velocities of the polymer-containing slurries thanslurries containing the same concentration of potash but without thepolymer.

EXAMPLE 1 Percent Accumulative Percent +35 mesh 9. 6 9. 6 35 +48 mesh16. 9 2'"). 5 -4S +65 mesh 20. 9 47. 4 -+i5 mesh 19.9 07. 3 100 +200mesh 22. 4 S9. 7 200 mesh" 10. 3 100. 0

Settling tests were conducted by adding the slurries to the graduate.The slurry was added up to the 1.000 ml. mark of the graduate to give aslurry column about 265 mm. or 10.4 inches high. The results showed aclear effluent-slurry interface that was pronounced and readilyfollowed. To facilitate recording the settling data a grad uated(inches) strip of paper was attached to the outside surface of thegraduate with the zero graduation indexed at the meniscus of the slurry.The descending clear efiiuent-slurry interface was illuminated by aspotlight directed toward the graduate from the front. Prior to takingmeasurements the graduate containing the slurry was agitated vigorouslyfor several minutes to disperse the potash particles. Immediatelythereafter the descent of the clear efiiuent-slurry interface wasobserved and followed downward in inches per minute. The runs were madewithout added polymer. The settling of the solids was unhindered, thesediment was stratified and compacted.

FIGURES 1, 3 and 5 give the pertinent data in graph form from thesecontrol runs.

EXAMPLE 2 Additional settling tests were performed with the additionaluse of Leduc oil besides the oils used in Example 1. The No. 1 specialstandard potash was used to make slurries containing 30%, 40% and 50% byweight of potash solids. The settling characteristics of the slurrieswere measured with and without the addition of a polymer of methyl vinylether and maleic anhydride (commercially available as Gantrez AN 169).The polymer was incorporated in methyl alcohol to give a 0.1% solutionwhich was added to the oil so that the slurry contained 0.02 pound ofpolymer per ton of dry solids.

Pertinent data from the runs follows:

Weyburn Oil 30% 40% 50% Solids Solids Solids Specific gravity, oil,g./cm.'- 0. 878 0.878 0.878 Specific gravity, slurry, g./cm." 1. 0551.132 1. 221 Oil viscosity 19.6 at 22 C. Slurry viscosity withoutpolymer..- 28. 5 39. 6 111. Slurry viscosity with added polymer 120.0Average particle size, mm- 0. 218 0.218 0.218 Maximum particle size, mm.0. 420 0. 420 0. 420 Average settling velocity of slurry withoutpolymer, tt./sec 0. 00161 0.00050 0.00035 Average settling velocity ofslurry with added polymer, it./sec 0.0023 0.0012 0.00017 LloydminsterNo. 1 Oil 30% 40% 50% Solids Solids Solids Specific gravity, oil,g./cm.- 1.064 1. 064 1. 064 Specific gravity, slurry, g./cm.- 1. 237 1.308 1.390 Oil viscosity 13.3 at 22 C. Slurry viscosity withoutpolymer... 17. 0 52. 129.0 Slurry viscosity with added polymer 136. 0Average particle size, mm 0.218 0.218 0. 218 Maximum particle size, mm0. 420 0. 420 0. 420 Average settling velocity of slurry withoutpolymer, it./sec 0.0011 0.00052 0. 00016 Average settling velocity ofslurry with added polymer, ft./sec 0. 00208 0. 00046 0. 00018Lloydminster No. 2 Oil 30% 40% 50% Solids Solids Solids Specificgravity, oil, g./cm.'- 0.910 0.910 0.910 Specific gravity, slurry,g./cm.- 1.088 1.164 1.251 Oil viscosity 86.5 at 22 C. Slurry viscositywithout polymer... 328.0 450. 0 Average particle size, mm 0.218 0.218 0218 Maximum particle size, mm 0. 420 0. 420 0 420 Average settlingvelocity of slurry without polymer, it./sec. .0004 0.00021 0. 000051Average settling velocity of slurry with added polymer, it./sec 0.00016This data shows that the slurries containing the polymer settled aboutas fast as the slurries containing no polymer. However, the slurriescontaining the polymer did not give stratified layers of potash uponsettling, as did the slurries containing no polymer, and the potash inthe polymer-containing slurries did not compact upon settling.

EXAMPLE 3 Percent +100 +200 16.6 200 83.4

This material had been run through a high speed hammer mill and had alarge percentage of solids in the 1 to 74 micron range.

The screen analysis of the final potash mixture (90% No. 1 specialstandard potash and of l00 mesh potash fines) was:

Mesh Percent The 10% of fines was incorporated into the slurry tosimulate the accrued fines of attrition which would nor mally be foundafter transportation in a pipeline.

A polymer of methyl vinyl ether and maleic anhydride (commerciallyavailable as Gantrez AN 169) was incorporated in methyl alcohol to givea 0.1% solution which was added to the oil so that the resultingslurries contained 0.02 pound of polymer per ton of dry solids.

Settling tests were conducted by adding the slurries to a graduate as inExample 1 and the procedure therein followed. The settling of the solidswas hindered, the sediment was unstratified and free of compaction.Graphs of the data obtained are shown in FIGURES 2, 4 and 6. Bycomparing FIGURE 1 with FIGURE 2, FIGURE 3 with FIGURE 4, and FIGURE 5with FIGURE 6 it will be seen that the potash compacts far more when thepolymer is not used than when it is included in the slurries. The vastlydifferent settling characteristics of the slurries with and without thepolymer are best appreciated by actual observation of the materials in asettling test. Words and figures are not fully capable of adequatelycommunicating this difference. Full comprehension requires observationof the settling slurries.

EXAMPLE 4 A slurry containing 50% No. 1 special standard potash asdescribed in Example 1 in Leduc oil having a viscosity of 5.0 at 22 C.and 0.02 pound of Gantrez AN 169 per ton of dry solids was prepared. Theslurry was tumbled in a laboratory size ball mill with only lifters inthe mill for approximately 48 hours. At normal speeds of 10 feet persecond, this would be equivalent to transporting the slurry about 340miles in a pipeline. After this treatment the slurry was transferred toa settling cylinder and the settling observed. Visual observation showedthere was no change or breaking up of the floc from the tumbling action,indicating that the dispersion will not be destroyed duringtransportation in a pipeline.

The foregoing detailed description has been given for clearness ofunderstanding only, and no unnecessary limitations should be understoodtherefrom, as modifications will be obvious to those skilled in the art.

What is claimed is:

1. The method which comprises mixing particles of solid potash, anormally liquid petroleum product and a copolymer of methyl vinyl etherand maleic anhydride to form a slurry, said copolymer being present inan amount sufiicient to maintain said potash particles in suspension insaid petroleum product forcing the slurry through a pipeline to acollecting depot and separating the solid material from the petroleumproduct.

2. The method of claim 1 in which the copolymer incorporated in themixture is dissolved in a petroleum miscible solvent.

3. The method of claim 1 in which the slurry contains 25 to 50% byweight of potash.

4. The method of claim 1 in which the slurry contains about 0.005 toabout 0.50 pound of copolymer ton of potash.

5. The method of claim 1 in which the potash particles average no morethan 1.65 mm. in diameter.

6. The method which comprises thoroughly mixing together (l) potashparticles, (2) a normally liquid petroleum product and (3) a solution ofa copolymer of methyl vinyl ether and maleic anhydride dissolved in apetroleum product miscible solvent to form a slurry, said copolymerbeing present in an amount sufiicient to maintain said potash particlesin suspension in said petroleum product forcing the slurry through apipeline to a collecting depot and thereafter separating the potash fromthe petroleum product.

7. The method which comprises thoroughly mixing together (1) potashparticles, (2) a normally liquid petroleum product and (3) a solution ofa copolymer of methyl vinyl ether and male-ic anhydride dissolved in apetroleum product miscible solvent to form a slurry containing 25 to 50%by weight of potash and about 0.005 to about 0.50 pound of polymer perton of potash, forcing the slurry through a. pipeline to a collectingdepot and thereafter separating the potash from the petroleum product,said copolymer having a specific viscosity of about 2.6-3.5 asdetermined on a solution of 1 g. of the copolymer in 100 ml. ofmethylethylketone at 25 C.

8. The method of claim '7 in which the miscible solvent is methanol.

9. A slurry consisting essentially of a mixture of potash particles, anormally liquid petroleum product and a copolymer of methyl vinyl etherand maleic anhydride said copolymer being present in an amountsufficient to maintain said potash particles in suspension in saidpetroleum product.

10. A slurry consisting essentially of a mixture of potash particles, anormally liquid petroleum product and a solution of a copolymer ofmethyl vinyl ether and maleic anhydride dissolved in a petroleum productmiscible solvent said copolymer being present in an amount sufficient tomaintain said potash particles in suspension in said petroleum product.

11. A slurry according to claim 10 containing 25 to 50% by weight ofpotash and about 0.005 to about 0.50 pound of copolymer per ton ofpotash.

12. A slurry according to claim 11 in which the potash particles averageno more than 1.65 mm. in diameter.

113. A slurry consisting essentially of a mixture of 25 to 5 0% byweight of particles of potash, a normally liquid petroleum product and asolution of a copolymer of methyl vinyl ether and maleic anhydridedissolved in a petroleum product miscible solvent, the amount ofcopolymer in the slurry being about 0.005 to about 0.50 pound per ton ofpotash, and the copolymer having a specific viscosity of about 2.63.5 asdetermined on a solution of 1 g. of the copolymer in 100 ml. ofmethylethylketone at 25 C.

14. A slurry according to claim 13 in which the potash particles averageless than 1.65 mm. in diameter.

References Cited UNITED STATES PATENTS 9/1952 Cross 302-66 12/1962 Scott252--8.5

* UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,380 784 April 30, 1968 Parke O. Yingst et :11.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as shown below:

' Column 2, line 3, "is" should read it Column 4, line 10 "1 .000"should read l ,000 Column 5 line 72 "-65+65' should read -48+65 Column6, line 58, "copolymer" should read copolymer per Signed and sealed this28th day of October 1969.

(SEAL) Attest:

1 2mm M. Fletcher, Jr. WILLIAM E. SCHUYLER, JR.

At testing Officer Commissioner of Patents

